Adhesive backing



Patented May 13, 1930 LOUVERN G. LANGE, F PASSAIC, NEW JERSEY ADHESIVE BACKING 1T0 Drawing.

This invention relates to adhesives and has for its object the provision of certain improvements in the method of applying and using adhesives. More particularly the in- 5 vention aims to provide an improved adhesive coating for varnished or-oiled papers and an improved method of applying the same.

Bottle caps, covers, container sealing devices and the like frequently are provided with a thin strip of yieldable material between the cap itself and the neck of the bottle or jar. This yieldable material frequently is in the form of a thin sheet of natural or composition cork such, for example, as the insert of cork placed within the familiar crimped-on cap of beverage bottles. V

In the heretofore customary method of using bottle caps and the like it is frequently necessary or desirable to protect the cork insert from the action of the contents of the bottle or protect the contents of the bottle from the material of the cork insert. This is necessary because when composition cork is used, the binder of the fragments of cork is frequently soluble in the contents of the bottle,

thus contaminating the contents of the bottle.

- The natural cork contains imperfections and whenever the imperfections come in contact with the edge of the neck of the bottle there is a tendency for the contents to leak and the cork insert in the bottle cap fails to seal the contents of the bottle. This makes it desirable to employ some means for protecting the surface of the cork to cover up such imperfections as may occur in the surface adjacent to the edge of the bottle neck.

The cork insert or liner may be protected by a sheet of varnished paper, the unvarnished surface of which is bonded to the cork by a material such as gutta percha. The gutta percha in sheet form may be applied to the unvarnished surface of the sheet of'varnished paper and blanks may be stamped from this composite material and applied to the cork insert by hot pressing. I prefer to applythe gutta percha to the varnished paper in liquid form as hereinafter described, for in this manner it is possible to employ sufiicient gutta percha to accomplish the desired result without using as much varnished paper, or as Application filed July 3, 1929. Serial No. 375,588.

much gutta percha as is necessary when strips, or separate sheets of these materials, are combined as set forth above.

The gutta percha is customarily combined with other gums or substances in order to impart to the gutta percha other desirable properties. Balata gum and various other resins are frequently used for this purpose. Throughout this specification and the appended claim the term gutta percha is used to designate the adhesive material whether it be gutta percha alone or in combination with other substances which may slightly alter its properties.

Clean washed gutta percha may be dissolved in an appropriate volatile solvent such for example as highly refined gasoline, solvent naphtha, toluene,- benzene or Xylene. This solution is heated until the mass becomes thick and viscid in which state it is ap- 7 plied in a thin layer to the back of the varnished paper and the remaining volatile solvent permitted to evaporate.

This method of applying the gutta percha to the varnished paper permits an evenly distributed coherent layer to be applied of any appropriate thickness. The freshly dried gutta percha backing is preferably covered with talc or soapstone to overcome the tackiness of the fresh gutta percha surface.

The coating of gutta percha in solution in gasoline or other appropriate solvent is spread on the back of the treated paper or fabric in such a manner that after the solvent evaporates there is left as a backing on the treated paper a precipitated layer of gutta percha. The spreading of the solution may be so controlled that substantially any thickness of dried film may be attained. I have found it advantageous to use a finished film of substantially one thousandth (.001) of an inch in thickness with many materials, as this provides an appropriate thickness to give thoroug 1 adhesion when the paper is hot pressed on another article.

The film of gutta percha deposited from solution may be treated in any advantageous manner to eliminate the tackiness of the freshly exposed surface. I have found it advantageous to dust the surface thoroughly 100 percha.

with powdered talc or soapstone. The adhering layer of powdered material does not materially impair the adhesion of the gutta percha film when applied by the hot pressing method for te powdered particles are then incorporated in the body of the melted gutta The use of varnished paper provides a laminated or multi-ply fabric of great tensile strength, for the film of varnish attached to one side of the paper, the toughfibres of the paper itself and the layer of gutta percha adhering to the back of the treated paper and the other article each provides, an element of added strengthto the laminated or multiply assembly. a

The solvent method of applying the gutta percha. reduces the cost of the finished fabric not only by appreciably reducing the thickness of the gutta percha film, but also by reducing the cost by providing a more economical method of handling and preparing'the materials. The gutta percha may be applied in any appropriate manner, 'as for example, by spreading, flooding, brushing or spraying.

I have found in the practice of the invention that the type of paper used has a great bearing on the finished material. I have found it advantageous to use a paper which has a high gloss or a polished surface. This type of paper usually has a coating of very fine material which fills in the pores of the paper itself so that the adhesive backing which is appropriately placed on the paper does not absorb into the body of the paper as readily as when one of the softer more open grained papers is used. In other words such paper is heavily sized. Thus the adhesive backing remains for the most part on the surface of the paper and does not penetrate to any large extent into the body of the material. The adhesive backing on this type of paper is thus substantially all available to be used as an adhesive to bind the I paper to any other material when it is ap propriately applied by means of pressure and heat.

The composite material of the present invention is far superior to any composition, or composite material, heretofore employed as a liner or filler for bottle caps and the like. It is an established fact that even the best grades of varnished paper will absorb moisture to the extent of 12 to 13 per cent and, accordingly, the use of varnished paper in making bottle cap liners, as heretofore sug gested, has been a failure. Even though the varnished paper may form an air-tight seal, yet moisture penetrates the varnished paper and attacks the underlying material, and the contents of the container is no longer effectively sealed.

The use of metal foil as a cover for corkfactory, not alone from the standpoint of the high cost'of the metal foil, but also because the foil is an extremely weak material mechanically and is easily ruptured by any irregularities in the edge of the container, or by excessive pressure applied to the cap or cover enclosing the container. Attempts have been made to provide a soft cushion for the metal foil but such practice is not a satisfactory solution of the problem because of the expense of the cushion material and the fact that such precautions fail to prevent rupture of the metal foil under abnormal conditions. The foil must be very thin in order to be sufliciently flexible to conform to the configuration of the top of the container and it is impossible to make foil complying with such requirements withouthaving the foil very weak mechanically.

The applicant has found that he can eliminate entirely the use of metal foil and at the same time provide a perfect seal for the container. In general this result is accomplished by employing a continuous film of varnish and a continuous film of gutta percha which functions as a Waterproof adhesive. Paper, or the like, may have one surface provided with a continuous film of varnish and the other provided with a continuous film of gutta percha and this composite material may be bonded to an underlying layer of cork, or other resilient ma terial. As pointedoout above, the paper is preferably heavily sized to insure continuity of the films of varnish and gutta percha. The varnish film is adapted to come in contact with the contents of the container and prevent the contents from coming in contact with the g'utta percha film, except in so far as moisture from within the container penetrates the varnish film and reaches the gutta percha. The moisture however cannot penetrate the gutta percha and thus it appears that a perfect seal may be formed.

he penetration and character of the finished adhesive backing is also very largely dependent upon the type of solvents which is used to dissolve the mixed gums. These solvents also have a more or less permanent effect upon the precipitated adhesive. I am not certain whether this difference is due to the fact that certain solvents are retained for p a longer period by some of the gums used or whether some of the solvents promote a more thorough and complete mixture of the gums themselves. It would seem more likely that the latter is the true explanation of the difference in the adhesive backings, for it is not likely that all of the gums are equally soluble in a single solvent, but with the mixed solvents there is an intimate mixture of all the gums used. The rate of evaporation of the solvents may have something to do with the physical characteristics of the finished adhesive and by an appropriate mixture of solvents almost any desired rate of evaporation may be obtained.

I do not wish to confine myself to any specific mixture of gums or solvents for the adhesive backin must be able to take careof a wide range 0 conditions. These conditions may be atmospheric or temperature conditions, thus a harder adhesive may be made to withstand summer usage or transportation conditions which may be very severe. In shipping the finished material across the United States at certain times of the year, portions of the desert districts in the West are extremely hot and this heat might cause the disintegration or sticking of a'verysoft or low melting point adhesive.

At certaifiifimes the adhesive backed-"ma terial may be used under very cold conditions.

in this case the unwinding of the rolls might cause cracking of the paper itself due to the extreme stiflfness of the adhesive backing. Thus it will be seen that the adhesive backing may comprise different gums mixtures of gums in order to take care of extreme climatic or thermal changes.

The thickness of the adhesive coating may be varied in order to meet difierent conditions of use. \Vhen the material is to be applied to a very porous medium such as felt, cardboard, or even some grades of cork, it is advisable to use a thicker coatin of adhesive than when the adhesive backe material is to be applied to some impervious material in the nature of metal. I have found it advantageous to use an adhesive backing of from .001 to .002 of an inch in thickness, and have found that this thickness of adhesive backing is adequate for average conditions of use although a greater thickness has at times been a used in order to meet adverse conditions.

The cost of applying and usin an adhesive backing of .002 of an inch in thic ess or even greater thickness is less than the cost of using a thin sheet of gutta percha of the same thickness, for the waste in the adhesive backed material is substantially nil. The waste in using the thin gutta percha sheets is considerable because these sheets are delicate and are easily torn in handling, so that it is more advantageous to use a thickness of the same character with the material sprayed on or definitely attached to the paper in the manner of the present invention than it is to use the same thickness of percha.

My improved composite material comprising paper, which has been preferably heavily material with sheets of gutta,

having a high gloss and having a coating of varnish on one surface of the paper and a coating of gutta percha on the other surface thereo y In testimony whereof I afiix m signature.

LOUVERN G. ANGE.

or diiferent sized and having a varnished surface and a surface covered with gutta percha, is especially adapted for the purpose of providing liners or inserts for bottle caps, jar covers and the like.

I claim:

As a new article of manufacture, paper 

